"That's our focus this year," she tells TVGuide.com. "We're telling backstories and origin stories. We want to give everybody some insight into our heroes because we give insight to the unsubs every week. We're going to hit 200 [episodes] and it feels like, 'Let's tell the audience things they never knew before.'"

That involves an old beau for Garcia (Kristen Vangsness), The Reaper (C. Thomas Howell) and Haley (Meredith Monroe) returning (but not from the dead), and filling in the blanks of JJ's (A.J. Cook) year in the State Department during Season 6 — with some help from new BAU section chief Matt Cruz (Esai Morales), with whom she worked there. What's the deal with those two? How does Garcia's ex come back into the picture? Get the scoop on the season below:

1. Who is Matt Cruz?The BAU's new boss will make his debut in the fourth episode — Hotch (Thomas Gibson) will have filled in for Strauss (RIP!) over the summer — much to the shock of JJ, who didn't think they'd be working together again. "He lets her know pretty quickly that he didn't know he was up for the job. Somebody put his transfer on the fast track and they're not sure if that's because of their history together or what. He's definitely not necessarily seeking the job, but happy to have it," Messer says. So what is Matt like? "He's more, 'I'm one of you guys,'" she says. "We didn't want him to be the same as Strauss because then you're just retelling those stories. He comes in with mystery to the audience and the team."

2. JJ + Cruz sitting in a tree?It's not what you think! JJ and Cruz have a "quite a past" from their time together in the State Department, Messer says, but it's one that no one else can know about. "They cannot tell anyone what happened and they don't tell the team that they know each other," Messer says. Their suspicious behavior will prompt people to raise eyebrows though. "I think everybody will jump to, 'Are they having an affair? Why are they so close?'" Messer says. "I think everyone who knows us knows we wouldn't do that. I think people will wonder that though, but it won't be an affair. I promise!" 3. Happy 200th!The truth about JJ and Matt will be revealed in the series' 200th episode midseason. The episode will utilize the present-day/flashback framing device the show previously used in two other big episodes: the 100th and Prentiss' (Paget Brewster) return in the Season 7 premiere. "There's no hearing in this one like in those two, but different characters flash back to fill in the blanks to solve the present-day case, which is JJ in jeopardy," Messer teases. "200 is flashback-heavy, but with things fans who've watched all 199 will be happy with. Our goal is to reward everyone who's been with us for 200 episodes."

4. When Garcia met HotchSpeaking of flashbacks, Garcia's origin story in the 12th episode will time-warp us back to 2004 before she was in the BAU (yes, even before Reid [Matthew Gray Gubler] called her Gomez in "Tabula Rasa.") "It's basically her introduction to Hotch and that leads us to a present-day case," Messer says. "We get to meet the guy that was in her life back in 2004 when she had this serious boyfriend. It's a neat way to explore characters we know and love and to show a different side of them."5. The ex factorGarcia's old flame won't appear in the 2004 flashback, but in present day, when he'll meet the team. Does that include Garcia's on-again, off-again beau Kevin (Nicholas Brendon)? "He meets everyone," Messer says. "It's going to be interesting because it will have been a while since they've seen each other, and it was a bad breakup, but [they were] intense, intense, intense." 6. Sweet dreamsAs previously reported, The Reaper and Haley will appear in Hotch's dream in the fifth episode. The story line was concocted to mark 100 episodes since The Reaper stabbed Hotch. "I wanted to pay some respect to that story line, and here we are 100 episodes later and how is Hotch dealing with it?" Messer says. While we won't spoil exactly how that dream comes about, be prepared to see quite a few sweet moments between the former Mr. and Mrs. Hotchner. "After the read-through, we were like, "Oh, my God! I don't want to this to end,'" Messer says. "I'm sure everyone has had a dream where they didn't want to wake up because they felt good in that dream. You definitely feel that with Hotch not wanting to not see Haley again."7. Basics on BlakeHaving been introduced last season, Blake (Jeanne Tripplehorn) is the one member with whom viewers are least familiar, her long-distance relationship and history with Strauss and The Replicator notwithstanding. But that will change when her family drops by. "It won't be a flashback, but you will understand after meeting her family why Blake became who she is in the FBI," Messer says. "We really want to flesh out Blake more this year. We didn't do it that much last year."

8. Is love in the air?Garcia will always be Morgan's (Shemar Moore) baby girl, but he might have his own lady in his life. "There's a line in the premiere where someone says to Morgan when they're called in for the case, 'You were supposed to be on a date, and Morgan says, 'Yeah, she's my neighbor.' So we're trying to pay that off with a girlfriend later on," Messer says. Key word being "trying." "We haven't really landed on doing it yet, but Morgan for nine years hasn't been open about his personal life, so you need to earn why he'd be talking about his dating life now." As for Rossi (Joe Mantegna) and Reid, both of whom lost somewhat significant others last season, the plan is for them to remain single this year. "We'll tell their backstories too, but not like that. Everybody will get serviced."9. To be continued...Because Criminal Minds wasn't renewed for a ninth season until the 11th hour due to Messer's and several actors' contract negotiations, Season 8 was one of the rare times the show did not end a season on a cliff-hanger. Instead, Season 9 will open with a two-parter, featuring Camryn Manheim as the unsub. "It's a classic Criminal Minds premiere where everything's happen so fast that you don't have time to think. But it was funny not having to do a 'Previously on Criminal Minds...'[recap]," Messer says. But with two-year options in place, you can probably expect a cliff-hanger for the Season 9 finale. "We're not thinking that far ahead yet, but we do want to do a cliff-hanger," Messer says. "So hopefully we'll get an early pickup so we can."Criminal Minds premieres Wednesday at 9/8c on CBS.(Full disclosure: TVGuide.com is owned by CBS.)